The present invention relates generally to surgical instruments, and more particularly to surgical retractor, instrument mount, and tissue stabilizer devices for use during coronary artery bypass graft surgery.
Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death throughout the world. The cost to society from such diseases is enormous both in terms of the number of lives lost as well as in terms of the costs associated with treating patients through traditional surgical techniques. A particularly prevalent form of cardiovascular disease is a reduction in the blood supply leading to the heart caused by atherosclerosis or other condition that creates a restriction in blood flow at a critical point in the cardiovascular system that supplies blood to the heart.
Treatment of such a blockage or restriction in the blood flow leading to the heart is, in many cases, treated by a surgical procedure known as a coronary artery bypass graft (CABG) procedure, more commonly known as a xe2x80x9cheart bypassxe2x80x9d operation. In the CABG procedure, the surgeon xe2x80x9cbypassesxe2x80x9d the obstruction to restore normal blood flow to the heart either by attaching an available source vessel to the obstructed target coronary artery or by removing a portion of a vein or artery from another part of the body, to use as a graft, and installing the graft between a point on a source vessel and a point on a target artery.
To restore the flow of blood to the heart, the CABG procedure requires that a fluid connection be established between two vessels. This procedure is known as an xe2x80x9canastomosis.xe2x80x9d Typically, a source vessel, such as a source artery with an unobstructed blood flow, i.e., the left internal mammary artery (LIMA), or a bypass-graft having one end sewn to an unobstructed blood source such as the aorta, is sewn to a target occluded coronary artery, such as the left anterior descending (LAD) artery or other vessel, that provides blood flow to the muscles of the heart.
Although the CABG procedure has become relatively common, the procedure itself is lengthy and traumatic and can damage the heart, the cardiovascular system, the central nervous system, and the blood supply itself. In a conventional CABG procedure, the surgeon makes an incision down the center of the chest, cuts through the sternum, performs several other procedures necessary to attach the patient to a heart-lung bypass machine, cuts off the blood flow to the heart, and then stops the heart from beating in order to complete the bypass. The most lengthy and traumatic surgical procedures are necessary, in part, to connect the patient to a cardiopulmonary bypass (CPB) machine to continue the circulation of oxygenated blood to the rest of the body while the bypass is completed.
In recent years, a growing number of surgeons have begun performing CABG procedures using surgical techniques especially developed so that the CABG procedure could be performed while the heart is still beating. In such procedures, there is no need for any form of cardiopulmonary bypass, no need to perform the extensive surgical procedures necessary to connect the patient to a cardiopulmonary bypass machine, and no need to stop the heart. As a result, these beating heart procedures are much less invasive and the entire procedure can typically be achieved through a small number, typically one or two, comparatively small incisions in the chest.
Despite the advantages, the beating-heart CABG procedure is not universally practiced, at least in part, because of the difficulty in performing the necessary surgical procedures using conventional surgical instruments. For example, it has been difficult for the surgeon to access the required areas of the heart requiring revascularization. In addition, the various surgical steps that are required to be performed on the heart itself are more difficult to perform because the heart muscle continues to move and contract to pump blood throughout the duration of the procedure.
The specific portion of the surgical procedure that creates the anastomosis in the beating-heart CABG procedure is particularly difficult. Completion of the anastomosis requires placing a series of sutures through extremely small vessels on the surface of the heart while the heart muscle continues to beat. Moreover, the sutures must be carefully placed to ensure that the source vessel or graft is firmly attached and will not leak when blood flow through the vessel is established. In cases where the target coronary artery is temporarily obstructed, for example, to improve the surgeon""s visibility and avoid excessive blood loss, it is also important that the anastomosis procedure be performed rapidly to avoid ischemic damage to the heart.
Further adding to the difficulty of the procedure is the fact that the working space and visual access are often quite limited. The surgeon may be working through a small incision in the chest, for example, or may be viewing the procedure on a video monitor if the site of the surgery is viewed via surgical scope. The vessel, and particularly the arteriotomy to which a source vessel is to be anastomosed, may also be very difficult for the surgeon to see as it may be obscured more or less by layers of fat or other tissue.
The beating-heart CABG procedure could be greatly improved if the heart could be accessed and stabilized during the procedure such that the motion of the heart, particularly at the site of the anastomosis, is minimized even though the heart continues to beat and supply blood to the body. The beating-heart CABG procedure could be further improved if the target vessel, and specifically the arteriotomy was presented to the surgeon in a way that allows sutures to be easily placed.
In view of the foregoing, it would be desirable to have improved devices for accessing and effectively stabilizing the beating heart at the site of the anastomosis. It would be desirable to have a low-profile, atraumatic stabilizing device that stabilizes the beating heart at the site of the anastomosis and provides a favorable presentation of the target vessel and the arteriotomy. It would be further desirable to provide a mount for the stabilizing device, or other instruments, that allows the stabilizing device to be easily maneuvered to the desired position and orientation, fixedly secured until the procedure is completed, and then easily removed from the site of the anastomosis. It would also be desirable to have a retractor system for use in conjunction with the stabilizer that provides unobstructed and organized access to the areas of the heart requiring revascularization.
The present invention will be described for use in stabilizing the beating heart during CABG surgery, but the invention is not limited thereto, and is contemplated to be useful for other surgical procedures requiring body tissue or organs to be immobilized or stabilized.
The present invention involves various aspects of tissue stabilizer devices, and in particular a tissue stabilizer for use in immobilizing or stabilizing a portion of the beating heart using a compressive force delivered to the heart via the tissue stabilizer. The stabilizer may include a stabilizer base and a shaft. The shaft may be secured within an appropriate instrument mount preferably fixed to a retractor or other stable platform. The stabilizers of the present invention provide improved access to a surgical site at a target vessel on the surface of the heart and may include features which facilitate optimal presentation of the target vessel.
One aspect of the present invention involves an apparatus for stabilizing a localized portion of a beating heart comprising a base member having a wire frame coupled to the base member. The base member is preferably substantially rigid having at least one contact area adapted to frictionally engage the surface of the beating heart adjacent a first side of a target vessel. The wire frame may have a frame portion adapted to engage the beating heart adjacent a second side of said target vessel opposite to the first side and at least one leg portion connecting the frame to the base member. Preferably, the leg portion is substantially perpendicular to the frame portion. In a preferred embodiment, the frame portion is parallel to a central axis of the base member.
The leg portion is preferably flexible relative to the base member and may have a vertically relieved portion in the area where it would cross over the vessel between the contact area and the frame portion. In a preferred embodiment, the leg portion is formed from a unitary length of wire material. The wire material may be selected from stainless steel or titanium and may have a round or square cross-section. In one embodiment, the frame portion is vertically offset from the contact area, preferably by a distance of about 0.05 inches to about 0.2 inches. The contact area may be planar or curved to conform to the surface of the heart. The base member may have more than one contact area and most preferably two contact areas separated by an open space.
A shaft may be connected to the base member. Preferably, the base member of the stabilizer is operably connected to the distal end of the shaft. The shaft may be any configuration suitable for delivering the required compressive forces to the base member, but is preferably a substantially rigid shaft. The shaft may be straight, or more preferably, curved.
Preferably, the wire frame is moveable relative to the base member. In one embodiment, the base member includes a channel for slidably receiving at least a portion of the leg portion. The leg portion may have a plurality of detented positions with the channel. The detented positions may result from the channel having a plurality of teeth and the leg portion having a plurality of mating teeth adapted to engage the channel teeth. The position of the wire frame relative to the base member may be manually positioned between the detented positions.
The wire frame may be also be moveable using a rack and pinion arrangement, a threaded shaft and collar arrangement, or other like driving mechanism. In one embodiment, the base member includes a pinion gear having a plurality of gear teeth and the leg portion includes a rack having a plurality of mating teeth adapted to engage the gear teeth on the pinion. The wire frame can be moved in and out relative to the base member by rotating the gear. In another embodiment, the base member includes a threaded shaft rotatably coupled to the base member and the leg portion includes a collar having a threaded interior adapted to receive the threaded shaft. In that case, the wire frame can be moved in and out relative to the base member by rotating the threaded shaft causing the collar to move along the shaft.
The frame portion may have a first end and a second end each having a leg portion extending therefrom. Each leg portion may be removably attached to said base member. The base member may include a first and second channel for slidably receiving each leg portion. The wire frame may preferably be attached to from either side of the base member. When the wire frame is attached to the base member using two leg portions, the wire frame is preferably detachable from said base member to facilitate its removal from a completed anastomosis on the target vessel.
In another aspect of the present invention, an apparatus for stabilizing a localized portion of beating heart may include a base member having a post which is offset from the center of the base member. In a preferred embodiment, a substantially rigid base member is formed from a unitary piece of sheet material having a first side and second side. The base member may have a first section adapted to contact the surface of the beating heart and a second section at a fixed angle relative to the first section. The first section defines a first contact surface, a second contact surface and an open space between said first and second contact surface. A first end of the post is connected to the second section at a location which is offset from the open space between the first and second contact surfaces. A second end of the post terminates with at least a portion of a ball extending therefrom.
A shaft may be connected to the second end of the post. Preferably, the distal end of the shaft has a socket operably engaged with the portion of the ball at the end of the post. Preferably, the shaft is curved and substantially rigid.
In one embodiment, the angle between the first section and the second section may be from about 75 degrees to about 105 degrees, most preferably about 90 degrees, and the post is attached to and extends from the first side of the sheet material. In another embodiment, the angle is more than about 120 degrees and the post is attached to and extends from the second side of the sheet material.
In another aspect of the present invention, the apparatus for stabilizing a localized portion of a beating heart includes a substantially rigid base member having at least one surface adapted to contact the surface of the heart and a post having a first end moveably coupled to the base member and a second end having a ball or a ball-shaped member extending therefrom. A shaft, preferably a rigid shaft, may be provided with a distal end having a socket operably engaged with the ball.
In one embodiment, the base member has a first section having at least one surface for contacting the surface of a heart and a second section adjacent the first section. Preferably, the moveable post is attached to the second section. The second section may be at an angle relative to the first section. The second section may have a slot adapted to receive the first end of the post which is moveable within the slot from a first position to a second position.
In another embodiment, at least a portion of the base member has a curved outer profile and the post is mounted to a top member having an interior profile adapted to engage and concentrically rotate about the curved outer profile. The base member may have at least one elongate slot. The top member may have one or more extending features or tabs engaged within the slot or slots. Preferably, the interior profile of the top member is close fitting with the curved outer profile of the base member. Most preferably, the top member encircles more than 180 degrees of the base member thereby capturing the base member within the top member.
In another aspect of the present invention, the apparatus for stabilizing a localized portion of a beating heart includes a base member having a post attached to a pivotable link member. Pivoting the link to one or more different positions correspondingly moves the post to one or more different positions, including positions offset from the center area of the base member in a right or left direction. In a preferred embodiment, the base member has at least one surface adapted to contact the surface of the heart. The link member may be pivotably coupled to the base member at a predetermined pivot point and has a first link end spaced a distance away from the pivot point. A first end of the post is attached to the first link end and a second post end includes at least a portion of a ball extending therefrom. A shaft, preferably a rigid shaft, may be operably coupled to the ball. Preferably, the shaft has a socket an a distal end which engages the ball.
The link member may also have a second link end opposite the first link end. The second link end may be releasably locked to said base member to substantially prevent relative movement of the link member relative to the base member. The second link end is releasable such that the link member can be pivoted about the pivot point to allow the post to be moved from one position to another. Preferably, the link member pivots about a pivot pin extending from the base member. The base member may have a first contact surface, a second contact surface and an open space therebetween. The link member preferably provides a first position where the post is laterally offset from the open space in a first direction and second position where the post is laterally offset from the open space in a second direction. Thus, the post can be advantageously moved from a left-hand position to a right-hand position.
These and other features of the present invention will become more fully apparent from the following description and appended claims.